[mojo-edk] Add MojoWatch and MojoCancelWatch APIs

mojo/edk/system/awakable_list.cc

Index: mojo/edk/system/awakable_list.cc
diff --git a/mojo/edk/system/awakable_list.cc b/mojo/edk/system/awakable_list.cc
index 429e691a4c9e51a3d62e838885ff8e376f466dcf..2045f32dffa698984f3ed69148f43d142d5c89cd 100644
--- a/mojo/edk/system/awakable_list.cc
+++ b/mojo/edk/system/awakable_list.cc
@@ -39,6 +39,7 @@ void AwakableList::AwakeForStateChange(const HandleSignalsState& state) {
     }
   }
   awakables_.erase(last, awakables_.end());
+  watchers_.NotifyForStateChange(state);
 }
 
 void AwakableList::CancelAll() {
@@ -47,6 +48,7 @@ void AwakableList::CancelAll() {
     it->awakable->Awake(MOJO_RESULT_CANCELLED, it->context);
   }
   awakables_.clear();
+  watchers_.NotifyClosed();
 }
 
 void AwakableList::Add(Awakable* awakable,
@@ -70,5 +72,16 @@ void AwakableList::Remove(Awakable* awakable) {
   awakables_.erase(last, awakables_.end());
 }
 
+MojoResult AwakableList::AddWatcher(MojoHandleSignals signals,
+                                    const Watcher::WatchCallback& callback,
+                                    uintptr_t context,
+                                    const HandleSignalsState& current_state) {
+  return watchers_.Add(signals, callback, context, current_state);
+}
+
+MojoResult AwakableList::RemoveWatcher(uintptr_t context) {
+  return watchers_.Remove(context);
+}
+
 }  // namespace edk
 }  // namespace mojo